Igniter for sintering machines



July 2, 1929. .R. w. HYDE IGNITER FOR SINTERING MACHINES Filed May 21,1927 S-vwemtoz REED W- HYDE 951 mom, I M

Patented July 2, 1929.

UNITED STA ES PATENT oFFicE.

REED W. HYDE, F SUMMIT, NEW JERSEY, ASSIGNOR TO DWIGHT AND LLOYD SINTER-ING COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

IGNI'IER FOR SINTERING MACHINES.

Application filed May 21, 1927. Serial No. 193,134=.

This invention relates to a sintering maspaced insulators. This issecured to a suit 50 chine and more particularly to an igniting ableframework and supported a short disapparatus for initiating combustionin the tance above the surface of the charge in the layer of material tobe sintered. sintering apparatus so that the heat devel- In sinteringany material, the operation is oped will be directed and reflected ontothe started by igniting the combustible material ore surface. 55 at thesurface of the charge, as by applying Although the novel features whichare bea flame thereto for a brief period of time, lieved to becharacteristic of this invention after which combustion is propagated.will be specifically pointed out in the claims through the layer by theair currents drawn appended hereto, the invention itself, as totherethrough. The ignition should prefits objects and advantages, themode of its 60 erably be complete over the entire surface. operation andthe manner of its organization, uniform, rapid and superficial, whileavoidmay be better understood by referring to the ing fusing thematerial. following description taken in connection This inventionrelates specifically to means with the accompanying drawing forming afor igniting the charge by heat thrown on part thereof, in which likereference charac- 65 i the surface from an electrically heated ignitershave been used to denote like parts in tion device placed above andspaced somewhat the various figures. Since such illustration from thesurface of the charge. v It provides is, however, primarily for purposesof diseasily controlled means for effecting comclosure, it will beunderstood that the struc plete,uniform, rapid, surfaced ignitionwithture and the method of operation thereof 70 'out the undesirablefeatures of drying the may be modified in various respects withoutunderlying portion of the charge, overheatdeparting from the broadspirit and scope of ing and fusing the surface, unevenness of igtheinvention.

nition and similar faults. It eliminates the- One embodiment of theinvention has been constant attention required by oil, coal or shown forpurposes of illustration in the ac- 75 wood fired igniters, and thenecessity for companying drawing, in which compressed air, and expensivepiping and Fig. 1 is a broken elevationof a portion storage and pumpingsystems required by oil of a sintering machine constructed in acor gas.Once adjusted, it continues without cordance with the invention,

further attention so long as current is sup- P Fig. 2 is a section takenon the line 2-2 of 30 lied. y ig. 1, r p The invention also consists incertain new Fig. 3 is a detail view of a resistance eleand originalfeatures of construction and mcnt which may be employed and combinationsof parts hereinafter set forth Fig. 4 shows a modified form of resistorand claimed. element. The invention will be described in connec- In thefollowing description and in the tion with the well known Dwight andLloyd claims the various parts of the apparatus and straight linecontinuous sintering machine, details of the invention will beidentified by 40 but may obviously be adapted to other types spe ificnames for convenience, but they are of sintering apparatus. intended tobe as generic in their application An electrical resistor capable ofdeveloping as the art will permit. a high degree of heat, which may beformed Referring more particularly to the drawof a coil of resistancewire, a series of reings, pallets 10-may be elevated by sprocket 45sistance blocks, or other suitable resistor ma- .wheel 11 and propelledthereby along track tcrial, is secured to a backing plate such as 12,passing first under the hopper 13 and reasbestos lined metal, tile orother non-comceiving the ore to be sintered, then over a dead bustibleinsulating material, or may be supplate 14 and windbox 15, where thesintering ported on a metal backing plate by suitable operation takesplace. Plate 14 prevents with its forward end. slightly beyond thev bysupporting brackets, and should prefer- 'ably be adjustable verticallyand horizontally. A shield or hood 16 for the igniter, having a slot 24in the edge near the windbox, serves to keep off draught-s or wind-whichmight interfere by causing loss of heat, but permits entrance of airwhere such is desired.

The igniter should be supported. in such a locationthat it heats the topsurface of the ore charge in the pallets to ignition temperature, thatis to a temperature at which combustion of sulphur, carbon or othercombustible in the charge can take place, this heating beingaccomplished mainly before the ore layer reaches a point in its travelwhere appreciable volumes of air are drawn therethrough, and thenpreferably continuing for a brief distance thereafter. i

It is desired to heat the surface approximately to ignition temperaturewhile little or no air currents are passing therethrough, and then tocontinue this heating for a short time while air is being supplied. Thisprocedure avoids the great loss and waste of heat which would occur wereair drawn 'thru the layer during the entire warming up and heatingperiod, but insures the surface being maintained at ignition temperaturewhen the cold air blast first strikes it and until the combustibleconstituents commence to burn.

The ore charge first comes under the influence of comparatively lightinduced air currents at a point shortly before it reaches the beginningof the windbox, the air being drawn through it as indicated by thearrows. The exact point depends on various conditions, including degreeof suction and permeability of charge. At the windbox itself, the aircurrents are much more violent. Hence the mostfavorable location of theigniter is most easily determined, in any given case, by trial. As shownin Fig. 1, it is placed beginning of-the Windbox.

Since the degree of heat required for ignition is a. function of theparticular material being sintered, and varies widely with differentmaterials, it is obvious that it is a factor that must be considered inapplying an igniter in any individual case. Various means of adjustingthe heat are available such as, varying the length of the igniter,whichin connection with the rate of travel of the pallets determines thetime the ore is exposed to the heat. The spacing of the resistorelements or the strength of the electric current may also be controlledfor this purpose. Preferably the variable factors are so coordinatedthat the charge is subjected for only a brief period to a sufficientlyintense heat to raise the surface to theignition point, without dryingout the underlying portions of the charge, fusing the top surface, orcausing other undesirable results.

In operation, the current being turned on and the pallets movingforward, as the charge slowly passes under the igniter the surface isheated to the ignition point by the heat radiated and reflected down on;it from the resistor elements. Then, while this heating is stillmaintained, relatively light air currents are drawn through the chargewhich initiate combustion of the combustible ingredients. These aircurrents should at first be so light as not to chill the surface belowthe ignition point. This combustion raises the temperature still more,so that when the ore reaches the region of more violent air currentscombustion is progressing actively, and proceeds down through the layer,effecting sintering of the charge.

Fig. 4 shows another'form of igniter, having a curved shape, in order toreflect or focus the heat on the surface of the charge. This igniter maybe located at a greater distance above the surface of the charge, without loss of heating efficiency, and thereby avoid damage due toparticles of hot charge flying up into the air when ignited (as happenswhen sintering certain kinds of materials) and becoming attached to andpossibly short circuiting the resistor elements.

All forms of the igniter are so constructed as to prevent currents ofair from passing between or among the resistor heating elements. Thisavoids waste ofheatinheatingthe air currents before' the charge hasreached ignition temperature, and also insures longer life to theresistor, since air currents would tend to oxidize them and cause themto burn out more, rapidly. Also no plate or other obstruction 116 isinserted between the resist'or heating elements and the surface to beheated, thereby avoiding loss and wastage of heat.

a The igniter is so constructed and located as to insure most efficientand economical use 11: of the heat developed. The surface of the chargeis heated to a desired temperature before air currents begin to passthrough the layer under the influence of the suction means and this heatis maintained while relatively lat light air currents pass through thecharge to start combustion in the surface of the layer. When the moreviolent air currents are passing through the layer it will have passedbeyond the igniter, so that ignition heat will 12: not be wasted inwarming up these large volumes of air. The heat is concentrated on thecharge, where it will do the most good.

While this invention has been describedin connection with the continuoustype of sinter- '1 ing machine, it will be obvious that it is equallyapplicable to other types without departing from the spirit of theinvention. For example it may be applied to stationary sintering pans bymaking the igniter of asize corresponding with the surface area of thepan, and mounted on a movable frame. In operation, the pan being chargedwith material to be sintered, the igniter may be set over the pan andthe electric current turned on. After a brief interval when thecombustible ingredients in the surface of the charge have been heated toignition temperature, the suction device may be started and air currentsdrawn through the charge after which the electric current may be turnedoff, the igniter removed and the sintering operation continued.

While certain novel features of the invention have been shown anddescribed and are pointed out in the annexed claims, it will beunderstood that various omissions, substitutions and changes in theforms and details of the device illustrated and in its operation may bemade by those skilled in the art without departing from the spirit ofthe inven tion.

What is claimed is:

1. An electric ignition device comprising a resistance element capableof being heated to a high temperature by passage of an electric currenttherethrough and means for reflecting the heat developed thereby ontothe surface to be ignited and for preventing circulation of air currentsabout the resistance element, and

means for shielding a portion of the surface to be ignited from aircurrents and permitting light air currents to pass over another portionof said surface.

2. A resistance device comprising a series of resistance elementsarranged in parallel relationship and adapted to extend over a'substantial area and means for reflecting heat developed thereby ontothe surface to be ignited and for preventing circulation of air currentsabout the resistance elements, and v means for shielding a portion ofthe surface to be ignited from air currents and permitting light aircurrents to pass over another portion of said surface. 3. A resistancedevice comprising a plurality of resistance elements arranged inparallel relationship and extending over a substantialarea, anadjustable support for said elements and a reflector for reflecting andfocusing heat upon the material being ignited and for preventingcirculation of air currents about the resistance elements.

4. In combination with a sintering machine including a plurality ofpallets, a wind box, means for passing successive pallets thereover,

, and an electrical ignition device adapted to reflect heat upon thecharge in said pallets and to ignite the surface thereof prior to thepassage over said wind box.

5. In combinationwith a sintering machine including a plurality ofpallets, a wind box and means for passing successive pallets thereover,an electrical ignition device adapted to radiate heat onto the surfaceof said pallets for igniting the material therein and so lo.- cated asto heat the surface of said material to ignition temperature beforesubstantial amounts of combustion supporting gases are caused to passthrough said material into said -wind box.

6. A sintering machine having'a plurality of movable pallets, saidpallets having perforate bottoms, electrical means for ignitingcombustible materials contained in said pallets, means for passing acomparatively small amount of combustion supporting gases therethroughfor initiating'combustion and means for passing a comparatively largevolume of said gases therethrough for completing said combustion afterignition.

7 In combination with a sintering machine, a plurality of movablepallets, means for reflecting a suflicient amount of electricallydeveloped heat upon said pallets to bring the surface of the layer ofmaterials therein to ignition temperature, means for thereafter passinga comparatively light current of combustion supporting gas through saidmaterial for initiating combustion, and means for continuing theapplication of heat thereto until combustion is Well under way and meansfor passing a comparatively large volume of said gas therethrough forcompleting the combustion after ignition.

8. In a sintering machine, a plurality of movable pallets havingperforate bottoms, an ignition device comprising an electric resistancecovering a substantial area, and adjustably supported above the surfaceof the material contained in said pallets, to radiate heat onto saidsurface, a wind box and means for passing strong currents of air throughsaid pallets while over saidwind box and means for successively passingsaid pallets under said ignition device and over said Wind box.

In combination with a sintering machine a plurality of movable pallets,means for reflecting a suificient amount of electrically developed heatupon said pallets to bring the surface of materials therein to ignitiontemperature, means for passing a comparatively light air current throughsaid material initiating combustion, means for continuing theapplication of heat thereto untilcombustion is well under way and meansfor passing a comparativel large volume of air currents therethrough orcompletion of combustion.

10. In combination with a sintering machine including a plurality ofpallets, a Windbox and means for passing successive pallets thereover.and electrical ignition device adapted to radiate heat onto the surfaceof said pallets for igniting the material therein and acting upon saidmaterial before it passes over said Wind box whereby air currents aretively small amount of air therethrough for largely revented frompassing through said initiating combustion and means for passing 1pallets uring the ignition period. I a comparatively large volume of airthere- 11. A sintering machine having a plurality through for completingsaid combustion.

of movable pallets, said-pallets having perfo- In testimony whereof Ihave hereunto set rate bottoms, electrically heated means for my hand.

igniting combustible materials contained in said pallets, means forpassing a compara- REED W. HYDE.

